Climate change is posing new challenges to conservation because management policies on protected coral reefs are less eVective than they were before the current ecosystem degradation. Coral reefs, the most diverse and complex marine ecosystem provide economic services for millions, but are seriously threatened worldwide because reef-building corals are experiencing bleaching phenomena and a steady decline in abundance. The resources of a Marine Protected Area (MPA) in Cartagena, Colombia, are in constant decline, despite a current management plan and on-site staV, urging new conservation actions. A multidisciplinary team gathered to evaluate management eVectiveness including biophysical, socioeconomic and governance indicators. Coral cover and Wsh diversity and abundance were low both inside and outside the MPA, which suggests a limited eYciency of management. Currently, the MPA is a reef with low coral cover and high algae cover as well as large dead coral areas, which are generally signs of highly degraded reef habitats. Live coral cover in the MPA was represented by pioneer coral species such as Agaricia tenuifolia and Porites astreoides. Nonetheless, 35% of the scleractinian species sampled in the area harbored more than one zooxanthellae symbiont, which suggests potential resistance and resilience against coral bleaching. Maintenance of trophic structure and functional diversity is an important endeavor that should be a priority for management in order to allow ecosystem resilience. Social and governance indicators showed low-income levels and few opportunities for communities living in and around the park, low governability, Biodivers Conserv (2009) 18:935-956 1 C weak communication among stakeholders and with authorities at diVerent levels. As a result, problems related to over exploitation of resources were commonplace in the MPA. These results reXect low adaptive capacity of communities to comply with restrictive conservation rules, showing that establishment of a protected area is a necessary but insuYcient condition to guarantee conservation goals. Ignoring the role of local communities only will exacerbate the problems associated with natural resources. Involvement of communities in strategic ecosystems management appears to be a requisite to improve eVectiveness of protected areas, and participatory strategies, such as co-management, oVer opportunities to improve governability while letting communities adapt to MPA needs.
Trophic cascades exist in numerous terrestrial systems, including many systems with ants as the top predator. Many studies show how behavioral modifications of herbivores are especially important in mediating species interactions and trophic cascades. Although most studies of trophic cascades focus on predator-herbivore-plant links, the trophic cascades concept could be applied to almost any level of trophic interactions. Especially considering the importance of parasites we consider here the interactions between the parasitic phorid fly, Pseudacteon sp. (Diptera: Phoridae), its ant host, Azteca instabilis (F. Smith) (Hymenoptera: Formicidae), and the herbivore, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in the coffee agroecosystem. We investigated the effects of phorid flies on ant behavior by monitoring ant recruitment to tuna baits over a 30-min period in the presence or absence of phorid flies. To study the indirect effects of phorids on larvae, we placed baits on coffee plants to elevate ant foraging levels to levels near to ant nests, placed larvae near baits, and recorded the effects of ants on larvae either in the presence or absence of phorid flies. We found that phorid fly presence significantly reduced ant ability to recruit to baits through behavioral modifications and also significantly lessened ant ability to attack, carry away, or force herbivores off plants. We conclude there is a behaviorally-modified species-level trophic cascade in the coffee agroecosystem, with potentially important effects in ant and herbivore communities as well as for coffee production.
Recent reports show importance of pollinators to coffee and importance of ants as pollinators or floral protectors in many systems. Arthropod and pollinator diversity, however, declines with management intensification of coffee (Coffea arabica) agroecosystems. We investigated influences of both flying pollinators and ants on coffee fruit set and fruit weight in one highshade (high-biodiversity) and one low-shade (low-biodiversity) coffee farm in Chiapas, Mexico through exclusion experiments. Contradictory to previous reports, flying pollinators alone did not affect coffee fruit set or fruit weight. Individual fruit weights, however, were higher on branches with both ants and flying pollinators (1.78 g ± 0.312 (SE)) compared to branches without ants (1.03 ± 0.029) or branches without ants or flying pollinators (1.05 ± 0.049), but only in the highshade site. Although the mechanisms producing higher fruit weights are unknown, we discuss how ants or ant-flying pollinator interactions under high-shade coffee management may contribute to increased fruit weight and the implications of high-shade management for both sustainable coffee production and biodiversity conservation.
In developing countries, informal waste-pickers (known as scavengers) play an important role in solid waste management systems, acting in a parallel way to formal waste collection and disposal agents. Scavengers collect, from the streets, dumpsites, or landfills, re-usable and recyclable material that can be reincorporated into the economy's production process. Despite the benefits that they generate to society, waste-pickers are ignored when waste management policies are formulated. The purpose of this paper is to integrate the role of scavengers in a dynamic model of production, consumption, and recovery, and to show that, in an economy producing solid waste, efficiency can be reached using a set of specific and complementary policies: a tax on virgin materials use, a tax on consumption and disposal, and a subsidy to the recovery of material. A numerical simulation is performed to evaluate the impact of these policies on landfill lifetime and natural resource stocks. A discussion on the implementation of these instruments is also included.
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